1. Field of the Invention
At least one embodiment of the invention relates to a permanently or temporarily implantable device having an elongated electric conductor.
2. Description of the Related Art
Devices of this type, for example, electrode lines for electrostimulation, have the disadvantage that the electric conductor thereof can heat up in an MRI scanner because the alternating magnetic fields prevailing in the MRI scanner induce not inconsiderable electric currents in the electric conductor. Induced currents of this type can also be emitted via electrode poles of the electrode line to surrounding tissue and thus, for example, lead to undesirable heating of the tissue. For this reason, nowadays patients with cardiac pacemakers usually cannot be examined, or can be examined only to a limited extent, in an MRI scanner.
At least one stimulation electrode line is typically connected to implantable cardiac pacemakers or defibrillators (also referred to below jointly as cardiac stimulators or IPG (implantable pulse generator)), which stimulation electrode line has a standardized electrical connection at its proximal end provided for connection to the cardiac pacemaker or defibrillator and has one or more electrode poles on its distal end provided for placement in the heart. An electrode pole of this type is used to deliver electric pulses to the tissue (myocardium) of the heart or to sense electric fields, in order to be able to sense an activity of a heart within the scope of the so-called sensing. For these purposes, electrode poles typically form electrically conductive surface sections of an electrode line. Electrode poles are typically provided as an annular electrode in the form of a ring around the electrode line or in the form of a point electrode or tip electrode at the distal end of the electrode line. The electrode poles are connected in an electrically conductive manner via one or more electric conductors to contacts of the electric connection of the electrode line at the proximal end thereof. Thus one or more electric conductors run between the contacts of the electrical connection the electrode lines at the proximal end thereof and the electrode poles at the distal end of the electrode line, which conductors electrically connect one or more of the electrode poles to one or more of the contacts. These electric conductors can be used, on the one hand, to transmit stimulation pulses to the electrode poles and, on the other hand, to transmit electric signals recorded by means of the electrode poles to the proximal end of the electrode line and are also respectively referred to as a function line in the course of the further description. Function lines of this type are electric conductors necessary for the functions of the respective electrode line and as such are exposed to the risk of electric currents being induced in them through external alternating magnetic fields, which currents can lead, for example, to an undesirable heating up of the function lines or of the electrode poles connected to them or which can lead to the delivery of corresponding currents via the electrode poles to surrounding tissue and thus to a heating of the surrounding tissue.